Perpetual Motion Machine - 2

A perpetual motion machine of 2nd kind is not supposed to work as if in case of a thermal power plant with no condenser. But let us think of such a power plant, where the heat is rejected into the boiler itself. On first look the system tends to work. Energy is conserved. Lot of wasted heat is saved. Then why it does not work. What's the logical reason other than the KELVIN-PLANK statement...........

Replies

  • Kaustubh Katdare
    Kaustubh Katdare
    Another interesting discussion here. Could you explain why you think energy is conserved in the system that you're proposing?
  • VISHNUGOPAN
    VISHNUGOPAN
    Heat flowing out = work done + heat rejected to boiler
  • jav
    jav
    Heat directly cant flow from low to high temperatures or low to high pressures its nature that balls falls from top of the building to the ground and not the reverse until you give some power, this is the case in nature heat flows from high to low only, right from the bernoulli's formula which indicates the flow of pressure concept from high to low everything virtually indicates this and ENTROPY concept will explain each and every part of your question as you wish. Concluding, gas and liquid mixture from the turbine with intermediate pressure can't be fed directly to boiler which is at very high pressure and temperature.
  • Jeffrey Arulraj
    Jeffrey Arulraj
    I think if heat has to be transferred we need a medium this means more losses and less efficiency and the usual set up comes into the picture
  • Ramani Aswath
    Ramani Aswath
    Because rain does not fall back up into the cloud. Water falls and does not go uphill. The Second Law of thermodynamics requires that there is a positive potential difference, be it temperature gradient, pressure gradient, voltage difference or chemical energy difference for movement of energy. This does not exist in the example provided. So the proposed scheme is invalid.
  • Ramani Aswath
    Ramani Aswath
    An update.
    This explains concepts: #-Link-Snipped-#
    This article goes into engineering details:
  • VISHNUGOPAN
    VISHNUGOPAN
    jav
    Heat directly cant flow from low to high temperatures or low to high pressures its nature that balls falls from top of the building to the ground and not the reverse until you give some power, this is the case in nature heat flows from high to low only, right from the bernoulli's formula which indicates the flow of pressure concept from high to low everything virtually indicates this and ENTROPY concept will explain each and every part of your question as you wish. Concluding, gas and liquid mixture from the turbine with intermediate pressure can't be fed directly to boiler which is at very high pressure and temperature.
    Ok, I agree. What if we are mixing the coolent from turbine with the hot coolent inside the boiler. Thus minimising heat loss to surrounding.....
  • VISHNUGOPAN
    VISHNUGOPAN
    bioramani
    Because rain does not fall back up into the cloud. Water falls and does not go uphill. The Second Law of thermodynamics requires that there is a positive potential difference, be it temperature gradient, pressure gradient, voltage difference or chemical energy difference for movement of energy. This does not exist in the example provided. So the proposed scheme is invalid.
    Sir, we need a temp gradient if we are using some material for HEAT CONDUCTION. But what if we are allowing a mass flow. Like mixing of super heated coolant with a less heated coolant. That doesn't requires a thermal gradient.........
  • VISHNUGOPAN
    VISHNUGOPAN
    jav
    Heat directly cant flow from low to high temperatures or low to high pressures its nature that balls falls from top of the building to the ground and not the reverse until you give some power, this is the case in nature heat flows from high to low only, right from the bernoulli's formula which indicates the flow of pressure concept from high to low everything virtually indicates this and ENTROPY concept will explain each and every part of your question as you wish. Concluding, gas and liquid mixture from the turbine with intermediate pressure can't be fed directly to boiler which is at very high pressure and temperature.
    Can you please clarify a little bit more.....👎
  • Jeffrey Arulraj
    Jeffrey Arulraj
    VISHNUGOPAN
    Ok, I agree. What if we are mixing the coolent from turbine with the hot coolent inside the boiler. Thus minimising heat loss to surrounding.....
    The pressure difference caused will blow the boiler up

    And the same thing is more or else used in Heat exchangers
  • Ramani Aswath
    Ramani Aswath
    VISHNUGOPAN
    Sir, we need a temp gradient if we are using some material for HEAT CONDUCTION. But what if we are allowing a mass flow. Like mixing of super heated coolant with a less heated coolant. That doesn't requires a thermal gradient.........
    The super heated fluid is inside the boiler, while condensed fluid is at the tail end of the turbine. What will make this get into the boiler against the boiler pressure? A higher pressure pump? How much power that needs? What do you gain in the end? Cooling the boiler fluid.
  • jav
    jav
    VISHNUGOPAN
    Ok, I agree. What if we are mixing the coolent from turbine with the hot coolent inside the boiler. Thus minimising heat loss to surrounding.....
    Coolant from turbine? Can you explain a little more?
  • VISHNUGOPAN
    VISHNUGOPAN
    jav
    Coolant from turbine? Can you explain a little more?
    Sorry. I mean the used steam
  • Ramani Aswath
    Ramani Aswath
    It is just water at atmospheric pressure. It can go into the feed water tank.
  • anjali zendre
    anjali zendre
    i think u want to tell if after expansion or power development. in outlet of turbine working fluid have already some amount of heat. so if we allow this heated working fluid directly in boiler we can save lot of heat loss, which occur by condenser.?
  • anjali zendre
    anjali zendre
    if i m right..then u also know about K-P statesman ..that exchange of heat can't be done with single reservoir.?
  • anjali zendre
    anjali zendre
    VISHNUGOPAN
    A perpetual motion machine of 2nd kind is not supposed to work as if in case of a thermal power plant with no condenser. But let us think of such a power plant, where the heat is rejected into the boiler itself. On first look the system tends to work. Energy is conserved. Lot of wasted heat is saved. Then why it does not work. What's the logical reason other than the KELVIN-PLANK statement...........
    if u want answer in way of work output then u know. it is not changing. be-cos superheated steam is interning in turbine. and it developing work.. then it going out. be-cos of work output and expansion process part of heat is utilize and left heat will go out from turbine with steam or working fluid and pressure also drop. so there no any Chang is occurring in turbine or power development process.
  • anjali zendre
    anjali zendre
    VISHNUGOPAN
    A perpetual motion machine of 2nd kind is not supposed to work as if in case of a thermal power plant with no condenser. But let us think of such a power plant, where the heat is rejected into the boiler itself. On first look the system tends to work. Energy is conserved. Lot of wasted heat is saved. Then why it does not work. What's the logical reason other than the KELVIN-PLANK statement...........
    now let's think about making a power plant like this there no have condenser and compressor.we r directly adding turbine to boiler by a simple pipe line. then u know well that in turbine outlet working fluid have low pressure and temperature then boiler.so it never be go in boiler automatically be-cos of energy level difference. so have need any device which can feed working fluid in boiler forcefully.
  • anjali zendre
    anjali zendre
    VISHNUGOPAN
    A perpetual motion machine of 2nd kind is not supposed to work as if in case of a thermal power plant with no condenser. But let us think of such a power plant, where the heat is rejected into the boiler itself. On first look the system tends to work. Energy is conserved. Lot of wasted heat is saved. Then why it does not work. What's the logical reason other than the KELVIN-PLANK statement...........

    so now we r adding a device like compressor between boiler and turbine be-cos pressure has to be maintain. so now we allowing working fluid from turbine to compressor then it compress the working fluid and feed in boiler.
    now can u feel what is happening. here vapor form of working fluid is much more then liquid form. this u can observe from Rankine cycle.so when we allow to compress this directly we have required more energy supply to compressor..be-cos we r compressing hot and less dens working fluid.so amount of working fluid which feed in boiler is less and energy requirement is more.

    now u can feel it is also affecting the work output or power development and efficiency of plant.
  • anjali zendre
    anjali zendre
    so now we want to maintain power output and less energy requirement on compressor so we have use a device which can make working fluid high dens so we have need to cool the working fluid so that it can convert in liquid form or more density form.then comparatively hot working fluid..cool working fluid easily compress and feed in more amount and feed of water can be possible by using less expensive device like pomp. but here also few amount of vapor is still there so it is Li til prob of power plant.
  • anjali zendre
    anjali zendre
    now i think u can feel why condenser is also imp for working of power plant?and why we can't feed heated working fluid directly after expansion or power development?
  • riteshbstkr
    riteshbstkr
    dear friend
    on basis of my knowledge
    Through turbine low press.steam flows than that of boiler press.
    and also by providing pump we can't pump a steam.

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